Digitizing system and touch sensitive screens that allow a user to operate a computing device with a finger and/or stylus are known. Typically, a digitizer is integrated with a display screen, e.g. over-laid on the display screen, to correlate user input, e.g. finger touch and/or stylus interaction on the screen with the virtual information portrayed on display screen. Position detection of the fingers and/or stylus detected provides input to the computing device and is interpreted as user commands.
U.S. Pat. No. 6,690,156 entitled “Physical Object Location Apparatus and Method and a Platform using the same” and U.S. Pat. No. 7,292,229 entitled “Transparent Digitizer” both of which are assigned to N-trig Ltd., the contents of both which are incorporated herein by reference, describe a positioning device capable of locating multiple physical objects positioned on a Flat Panel Display (FPD) and a transparent digitizer sensor that can be incorporated into an electronic device, typically over an active display screen of the electronic device. The digitizer sensor includes a matrix of vertical and horizontal conductive lines to sense an electric signal. Typically, the matrix is formed from conductive lines patterned on two transparent foils that are superimposed on each other. Positioning the physical object at a specific location on the digitizer provokes a signal whose position of origin may be detected.
U.S. Pat. No. 6,762,752 entitled “Dual Function Input Device and Method” assigned to N-Trig Ltd., the contents of which is incorporated herein by reference, describes an apparatus for user input to a digital system, comprising a first sensing system for sensing a user interaction of a first type, co-located with a second sensing system for sensing a user interaction of a second type. The first system may detect styluses and like objects using EM radiation and the second system may detect touch pressure. In one embodiment, touch detection is extended only to the lower part of the screen, in which the keyboard is likely to be located, whereas stylus sensing extends to the entire screen. It is described that such an embodiment leads to a reduction in the number of parts, and thus reduced cost coupled with greater reliability.
U.S. Pat. No. 7,372,455, entitled “Touch Detection for a Digitizer” assigned to N-Trig Ltd., the contents of which is incorporated herein by reference, describes a digitizing tablet system including a transparent digitizer sensor overlaid on a FPD. The transparent digitizing sensor includes a matrix of vertical and horizontal conductive lines to sense an electric signal. Touching the digitizer in a specific location provokes a signal whose position of origin may be detected. The digitizing tablet system is capable of detecting position of multiple physical objects and fingertip touches using same conductive lines.
US Patent Application Publication No. 20070062852, entitled “Apparatus for Object Information Detection and Methods of Using Same” assigned to N-Trig Ltd., the contents of which is incorporated herein by reference, describes a digitizer sensor and/or touch screen sensitive to capacitive coupling and objects adapted to create a capacitive coupling with the sensor when a signal is input to the sensor. In some embodiments, the digitizer sensor includes a series of activated electrodes and passive electrodes. An AC signal, e.g. a pulsed AC signal, sequentially activates each of the activated electrodes. In response to each AC signal applied, a signal is transferred, by capacitive coupling, to each of the passive electrodes. The presence of a finger or an object typically alters the signal transferred to some of the passive electrodes. In some exemplary embodiments described in this reference, to speed up report rate, the active electrodes are divided into a number of groups wherein the active electrodes in each group are activated sequentially but the groups work simultaneously. This is accomplished by applying AC signals with non-mutually interfering (orthogonal) frequencies to each of the groups working simultaneously.